[int32[]]$a = 100,200,300,400

# [int32]$length = $a.Length

# Write-Output $length

# for($i = 0; $i -lt $length; ++$i){
    
# }

$a[0..4]

$b = 0..9
$b[-3..-1]

# 这方法在PowerShell比Linux Shell要高级一点
$a = 0 .. 9
$a[0,2+4..6]